1. Field of the Invention
The present disclosure relates to a measuring method and system of device with backlight; in particular, to a brightness measuring method and system of device with backlight.
2. Description of Related Art
When the device with backlight provides the backlight for illuminating the legends of the device, usually the backlight fails to uniformly illuminate each position on the legends due to the obstruction of the wire structure between the backlight module and the legends of the electronic device. As shown in FIG. 1, FIG. 1 illustrates a legend of key on a keyboard with backlight. The inside circuit wire of the keyboard may pass exactly through the left side of the legend “Backspace” and obstructs the rear backlight source slightly, thus resulting in that the brightness of four letters “Back” is slightly lower than the brightness of the five letters “space”. In order to measure the effect of illuminating the legend of the device with the backlight of the device, in the current measuring method the image of the legend that is illuminated by the backlight will be photographed, then according to the brightness value of each pixel and a predetermined threshold value, a part of the legend and an outside part of the legend are divided.
Referring to FIG. 2. FIG. 2 illustrates a schematic diagram of a bi-level image corresponding to the legend “Backspace” as shown in FIG. 1 after photographing and division in accordance with the threshold value. Comparing FIG. 2 with FIG. 1, most of pixels displayed after sifting the brightness value of the pixel are accurately corresponding to the legend or the background outside the legend. However, the pixels corresponding to upper half of the first letter and the second letter “Ba” is determined as the part outside the legend due to the lower brightness value after sifting. Accordingly, when the user calculates the brightness of the legend “Backspace” illuminated with the backlight according to the pixels shown in FIG. 2, he may inappropriately neglect the pixels of the upper half of the letters “Ba” which originally belong to the part of legend but are viewed as the part outside the legend. Therefore, the total brightness of the legend is overestimated, wherein the part of insufficient brightness cannot be really presented. That is, the calculated total brightness of the legend “Backspace” is not correct. If the measured brightness is not correct, the structure design of the device under test (DUT) or the improvement of the backlight module will be affected.